In a ruling today that is expected to help propel the case to the nation’s top court, the California Supreme Court held that supporters of Proposition 8 do have standing to defend the constitutionality of the same-sex marriage ban voters enacted in 2008.

The standing ruling was rendered by California’s top court at the request of the San Francisco-based 9th U.S. Circuit Court of Appeals, which is considering the constitutionality of the same-sex marriage prohibition, the supreme court explains in its written opinion (PDF).

Because state officials have refused to defend the constitutionality of the law, it would be an abuse of discretion not to permit official proponents of the Prop 8 ballot initiative to do so, the supreme court wrote, “either as interveners or as real parties in interest, in order to assert the people‘s and hence the state‘s interest in the validity of the measure and to appeal a judgment invalidating the measure.

“In other words, because it is essential to the integrity of the initiative process … that there be someone to assert the state‘s interest in an initiative‘s validity on behalf of the people when the public officials who normally assert that interest decline to do so, and because the official proponents of an initiative … are the most obvious and logical persons to assert the state‘s interest in the initiative‘s validity on behalf of the voters who enacted the measure, we conclude that California law authorizes the official proponents, under such circumstances, to appear in the proceeding to assert the state‘s interest in the initiative‘s validity and to appeal a judgment invalidating the measure.

“Neither the governor, the attorney general, nor any other executive or legislative official has the authority to veto or invalidate an initiative measure that has been approved by the voters,” the opinion continues. “It would exalt form over substance to interpret California law in a manner that would permit these public officials to indirectly achieve such a result by denying the official initiative proponents the authority to step in to assert the state‘s interest in the validity of the measure or to appeal a lower court judgment invalidating the measure when those public officials decline to assert that interest or to appeal an adverse judgment.”

The decision today does not address the merits of the constitutional challenge to Prop 8, the supreme court notes.